We propose to identify and clone endogenous inhibitory molecules of interleukin 1. human Immunodeficiency virus (HIV) infected macrophages and macrophage cell lines release two inhibitors of IL-1, an 8 kD molecule and a 95 kD molecule. Poly (A)= mRNA will be prepared from these sources and cDNA libraries prepared in lambda gt11 expression vector. Clones will be screen with a rabbit antiserum that neutralizes the activity of the 8 kD inhibitor. Positive clones will be subcloned into Okayama-Berg expression vector and the activity of transfected Cos 7 cell supernatants tested. Interleukin 1 inhibitors have therapeutic potential for immunoinflammatory diseases. Study of these molecules may provide a better understanding of the pathogenesis of AIDS.